FI103288B - Method and machine for cleaning anode of electrolyte tanks - Google Patents

Abstract

A procedure and machine for cleaning the anodes of electrolytic tanks, said procedure comprising the operations of mechanically breaking the deposits on the surfaces of the anodes, detaching and separating the deposits, once broken, and then subjecting the plate of the anodes to a flattening operation. The procedure is carried out with a machine which includes at least one pair of cutting rollers (1), nozzles for supplying jets of water under pressure (2) situated above said rollers (1), two flattening plates (3) with flat opposing surfaces, and means of suspending and raising the anodes (13) between the rollers (1), nozzles (2) and plates (3). The plates (3) may be provided on their opposing surfaces with cutting grooves. <IMAGE>

Description

103288

Method and machine for cleaning the anodes of electrolytic tanks Förfarande ooh mask för rengöring av anoder av electrolyte tank 5

DESCRIPTION

The present invention relates to a process for the purification of anodes in electrolytic tanks, which is specifically designed for the purification of anodes used in processes in which non-ferrous metals such as zinc and copper are produced electrolytically. A further object of the invention is a machine for carrying out said purification process.

BACKGROUND OF THE INVENTION

During the electrolysis process, to produce the aforementioned metals, and in particular zinc and the like, a layer of sludge contained in the electrolyte, essentially consisting of manganese dioxide (MnO 2), is deposited on the anode.

This layer grows thicker over time and acts as an electrical resistance.

As the width of the layer increases, the voltage required to generate a certain electric current increases, which confirms that the precipitate increases electrical energy consumption and should therefore be removed in the most efficient way possible if optimum conditions in the electrolysis process are to be maintained.

30

Further, the thickness of the layer increases steadily until it reaches a certain limit, after which some dendrites are formed and, once they have begun, grow rapidly due to the fact that the conductivity is higher through them as a result of the "tip effect" 35 and their ever decreasing cathode distance. .

When one of these points contacts the cathode, a short circuit is formed. This short circuit always damages the anode, causing distortion or cavity 2,103,288 which, with the exception of the anode deterioration, means that lead has been transferred to the electrolyte and subsequently precipitated with zinc to produce it impure.

For these reasons, the anodes need to be cleaned from time to time in an effective and efficient manner to ensure proper electrical behavior and performance, and often enough to prevent possible short circuits that could contaminate zinc deposits.

Various methods of performing anode purification to prevent the above problems are already known, and among these, the following three are worth mentioning: a) Pressurized water jets; 15 b) For plates having smooth opposite surfaces between which the anode is placed and pressed; c) With metal brushes.

The first of these systems requires a device for supplying pressurized water, said device requiring good maintenance and causing additional water consumption. Further, the noise level during water jet cleaning is high and the result obtained is not completely satisfactory due to the different adhesive forces of the precipitates and the different contacting forces of the water.

"25

In one of these systems, the purification step is accomplished by pinching the anodes between two plates having parallel surfaces.

This procedure attempts to break the precipitates and remove them from the surface of the anode until they have been peeled off, making it virtually impossible to remove them.

Finally, in the third of these systems, cleaning is accomplished by consuming the precipitates with brushes equipped with a metal brush11a.

During the cleaning step, the surface of the anode is also worn to a certain extent, which causes its premature deterioration. Similarly, when the brushes are in use, the bristles wear progressively. This wear is 3,103,288 uneven, which means that the subsequent effect of the brushes on the anodes is uneven, causing irregular cleaning.

Whatever purification system is used, the anode is subsequently flattened because in electrolysis processes the surfaces of the anodes and cathodes must be smooth due to their proximity.

DESCRIPTION OF THE INVENTION

10

SUMMARY OF THE INVENTION The object of the present invention is to provide a method of cleaning the anodes which achieves a total and effective cleaning of said anodes without the risk of deterioration. Further, the method of the invention enables the purification of all types of anodes (laminated, cast, grooved, etc.) in a relatively short time.

It is a further object of the invention to provide a machine for carrying out an anode purification process and having the described properties and advantages.

20

According to the present invention, the cleaning process comprises, in combination, the following steps: a) mechanically breaking the precipitates on the anode surfaces by means of a set of shear lines on the deposits; b) removing and separating the broken precipitates from the anode surfaces with pressurized water jets; and c) flattening the anode plates.

According to the invention, the cutting lines are made with one or two pairs of parallel rotating rollers having a side surface provided with screw-cutting grooves, feeding the anode between said rollers, whereby the difference between the grooves of both rolls is kept approximately equal to the thickness of the anodes.

The difference between the rollers is that they do not penetrate the lead plate of the anodes when breaking the precipitates. This can be achieved by adjustable stops 35 which limit the minimum distance between rollers.

4, 103288

The release step by means of pressurized water jets can be performed using directed nozzle rows to act on both surfaces of the anode.

The method described according to the invention is carried out on a machine comprising at least one pair of parallel horizontal cutting rollers disposed at the same height, two sets of nozzles for positioning pressure water jets located above said rollers, two plates disposed above said nozzles each supported by their horizontal top axes 10 and having smooth opposing surfaces, and means for supporting and raising the anodes between the rollers, between the water jet groups and between the two plates.

The rollers are rotatable, their difference is adjustable and their side surfaces 15 are provided with standard-height, screw-like grooves. Preferably, the side surface of each cutting roller is provided with two symmetrical helical grooves, which start from the central center plane and extend towards the end portions of the rollers. In addition, the grooves of each roller run in a different direction from the grooves of adjacent rollers.

20

The machine may include two pairs of horizontal cutting rollers, which are located at different heights and have the aforementioned features.

Each pair of rollers is mounted on brackets that can be moved in a direction perpendicular to the max. · 25 rollers. These supports are connected by means of actuating cylinders, whose movement towards the rollers is limited by the thickness of the anode and impurity surface deposits.

The pressurized water supply nozzles and the flattening discs between them are in a symmetrical position with respect to the vertical vertical plane between the pair of rollers or rollers, the nozzles being directed towards said plane and the plates rotating about the support axis between closed and angled.

35 j i 5 103288

The anode support and lifting means consists of a hoist comprising a flat vertical body longer than the end of the anodes, said body being provided below, starting from its vertical sides, with opposing supports for supporting the ends of the anode head.

5

The deposition breaking and anode plate flattening steps can be performed together by two plates having one surface provided with fine ribs provided with a free cutting edge, said plates facing each other and simultaneously facing 10 anode surfaces one on each side to simultaneously form shear lines on the anodes flattening the sex.

BRIEF DESCRIPTION OF THE DRAWINGS

All features of the present invention will be explained in more detail below with reference to the accompanying drawings, which, by way of non-limiting example, illustrate one practical embodiment thereof.

20 In the drawings:

Figure 1 is a schematic side view of an anode cleaning machine for electrolytic tanks.

Figure 2 is a view similar to Figure 1 showing a possible assembly system for different parts of the machine.

Figure 3 is a schematic front view of the machine.

Figure 4 is a plan view of the cutting rolls of the machine shown in Figure 3.

Figure 5 is a sectional view taken along line V-V of Figure 4.

Figure 6 is a view similar to Figure 1 showing an alternative embodiment.

6 103288

Figure 7 is an inside view of a single plate forming part of the machine shown in Figure 6.

Fig. 8 is a sectional view taken along the line VII-VII in Fig. 7.

5

DESCRIPTION OF THE PREFERRED EMBODIMENT

The anode cleaning machine of the electrolytic tanks shown in Figs. 1-3 comprises parallel shear rollers 1, two groups of nozzles 2 for feeding pressurized water jets and located on rollers 1.

Two plates 3 are disposed on said nozzles and each of them is supported by their upper horizontal axes 4 and is provided with means 5 for supporting and lifting the anodes.

15

The rollers 1 rotate freely and are arranged in pairs, with the two rollers of each pair of rollers being at the same height and each pair of rollers being in the same vertical planes as shown in Figure 1. Further, the difference between each pair of rollers can be adjusted.

20

The rollers 1 are made of an acid-proof material and, as best seen in Figures 3 and 4, each consists of two halves 6 and 7, each of which is provided with a helical cutting groove with opposite threads. In addition, the rollers are arranged such that the grooves of the retractable rollers also have opposite threads.

Returning to Figure 1, the rollers 1 are mounted on brackets 8 which allow the difference between each pair of rollers to be adjusted. Finally, nozzles 9 can be installed near the rollers 1 for supplying pressurized water to purify said rollers.

The nozzles 2 can be arranged in two rows and supplied with pressurized water to remove the precipitates from the anodes after they have been broken by the cutting rollers 1.

35 7 103288

The plates 3 are mounted on brackets 10, which in turn are mounted on their above-mentioned upper axes 4. These brackets 10 can be connected by means of a top system of the dental device 11 which ensures synchronized angular movement between the brackets and the plates. The actuation of the supports 5 10 and their respective plates 3 can be effected by means of hydraulic cylinders 12.

The plates 3 mounted on the brackets 10 can be pivoted in a parallel closed position, shown in Fig. 1, with the opposite pins 10 of the plates facing the anode plate 13, and an angular open position 3a, shown by dashed lines where the brackets 10 and their respective plates are separated. lifting and lowering.

The mechanisms 5 for supporting the anodes (Fig. 3) may comprise a hoist consisting of a flat vertical body having a length greater than the end 14 of the anodes 13 and provided below its vertical edges with opposing projections 15 for supporting the ends of the anode end 14. The body 5 is provided with lugs 20 above which have holes for connecting support cables 17 passing through wheels 18 mounted on structure 19, said cables being connected to a drive mechanism. The body 5 is provided on its sides with sliding means 20 supported by vertical rails 21 which secure the movement of the body 5 while holding it in the correct position.

'· 25

Figure 3 shows the body 5a of the anode support elements in its lowered position ready to receive the end 14a of the anode 13a. As the anode support means 5 is lifted, the frame and the anode travel successively between a pair of rollers 1 and pressurized water supply nozzles 2 until they reach a raised position 30 between the plates 3.

•

Figure 2 shows in greater detail the structure 19 on which the wheels 18 are mounted and the configuration of the rollers 1 and the pressurized water supply nozzles 2.

As can best be seen in Figure 2, the opposite surfaces of the plates 3 are provided with lower recesses 22 and upper recesses 23 for attaching their lower stops or lower separators to the anode ends 14 and 8 103288 when said plates are in a parallel closed position.

As also shown in Figure 2, the machine may include a carriage 24 for transporting the anodes 5 and may position the anode in a proper position for picking up by a support means 5 which raises it between the rollers 1 and the pressure water nozzles 2 until they are between the plates 3. , where they are lowered again until they are released at the position corresponding to the carriage 24.

10

The speeds at which the anodes are raised and lowered are adjustable, and during these movements as they pass through various locations or locations, they trigger sensors capable of actuating various mechanisms for cleaning by means of cutting rollers 1, pressure water jets 2 and lithium-15 filling plates.

Fig. 2 shows a head 25 mounted in structure 19, from which brackets 10 carrying plates 3 are supported by horizontal shafts 4.

20

Each pair of rollers 1 is supported by parallel beams 26 mounted at their ends between end plates 27 and spacer 28 (Fig. 3), the structure 19 supporting said plates. The beams 26 of each pair of rollers 1 are connected at their ends by cylinders 29 (Fig. 4), with the use of said cylinders 25 to separate or bring the beams 26 and thus the rollers 1 closer to one another. The beams 26 are also provided with external counterweights 30.

The adjustable stops 31 are disposed between the end plates and the central plate 28 30 (Fig. 5), said stops limiting the minimum distance between the beams 26 · 'and therefore the minimum distance between each pair of rollers 1. The stops 31 are adjusted so that when the rollers are at a minimum distance, they do not form recesses in the lead plate of the anode. The stops 31 are adjusted to the anode width such that the helical cutting grooves of the rollers 35 only penetrate the deposited layer without penetrating the lead of the anode plate.

9 103288

The method of cleaning the anodes using the machine described begins with the arrival of a dirty anode which is placed by the anode transport carriage 24 (Fig. 2) ready to be picked up by the lifting device 5. The lifting mechanism in the lower position 5a (Fig. 3) picks up the anode 13a and begins to raise it at a predetermined constant speed. When, as it moves upward, the anode end 14 passes the first line or pair of rollers 1, these are brought together using cylinders 29 (Fig. 4) until they are spaced at a distance equal to the thickness of the anode lead plate previously set by the stops 31 (Fig. 5). In this way, the screw-like threads of the roll-10 are dug into the slurry layer deposited on the anode surfaces. Thereafter, as a result of upward movement of the anodes, the friction between them and the rollers 1 and their screw-cutting shear threads cause them to rotate and their screw-shear threads form a series of break lines or shear lines on the slurry layer deposited on the anodes.

As the anode end 14 passes between the upper pair of rollers 1, the same process is repeated to form shear lines on the precipitates which intersect with the shear lines formed by the lower pair of rollers. In this way, the layer of precipitate 20 is completely cut by a series of intersecting fractures.

While the rollers are in operation, water is continuously fed through the nozzles 9 (Figure 1) to keep the surface of said rollers clean.

The anode continues to rise with the deposition layer now cut, and as it passes through the nozzles 2, the flushing process begins with pressurized water sufficient to raise the entire deposition layer previously rolled by the rollers 1. This cleaning step affects the rate at which the anode is lifted because the slower the rise rate, the more energetic the cleaning with the anodes exposed to pressurized water jets * | for a longer period of time.

Finally, when the lifting means 5 reaches the upper limit position, the anode is disposed between the plates 3, which move successively from a parallel closed 35 position to an angular open position 3a. Each time the plates reach the closed limit position represented by solid lines in the silicon cartridges, they strike the anode surfaces and straighten or flatten its plate. The number of times the anode has to be struck can be determined with the selectors.

5 When the anode is straightened, it is calculated at a constant speed that is normally higher than the ascent rate.

Alternatively, the anode may be rinsed with pressurized water during counting to remove any particles from the lead plate which were left in the up flush and were removed by the plates 3 during the rectification step.

Finally, once clean, the anode is placed back in the carriage 24, which: automatically moves until the new dirty anode is in place to be picked up by the lifting device 5 for cleaning.

Figures 6 and 8 show an alternative embodiment of the machine in which the cutting rollers 1 and flattening plates 3 are replaced by two parallel plates 32 which, as best seen in Figures 7 and 8, have internal surfaces which are oblique grooves 33 with cutting sections edge. The two plates 32 are the same so that when they are placed; in contrast, the grooves of each cross.

The plates 32 are mounted by the drive cylinders 34 and 35, the cylinders 34 carrying the second plate being larger in section than the cylinders of the opposite plate. Below the position where the plates 32 are, there are a number of nozzles 2, such as in the embodiment described above.

When the anode 13 reaches its upper position lifted by the support means 5 (Fig. 6), it is located between the plates 32 and, when actuated by the cylinders 34 and 35, compress the anode 13 as the ruptures 33 break and simultaneously straighten or flatten the anode plate.

35 There are two independent systems for anode safety. One of them involves limiting the displacement of the plates 32 such that at a minimum distance of 103288 their difference is equal to the thickness of the anode. Another security system is based on controlling the maximum force that these two disks can provide between them. This is accomplished by controlling the hydraulic circuit which activates them.

5

A second set of nozzles is disposed above the plates 32 for supplying pressurized water.

The movement of the cylinders 34 is calculated such that at the maximum extension point 10 they touch the anode 13 without moving it from the center plane of the machine. Afterwards, the cylinders 35 are activated and, since they are smaller in section, cannot cause the cylinders 34 to move rearward, ensuring that the anode 13 is disposed along the central vertical plane of the machine.

15

The cleaning process on the machine shown in Figure 6 is similar to that described with reference to Figures 1-5 with respect to handling the anode for positioning it at the highest point between the plates 32. At this point, the cylinders 34 are operated until they reach their maximum projection, at which point the plate 32 contacts the anode 13. The opposing plate is then moved by the cylinders 35 until said plate is pressed against the anode 13 with all the force previously applied. The pressure exerted by the plates 32 on the anode 13, the time of application of this force, and the speed of movement of the plates are all adjustable.

V 25

The compression effect of the anode 13 achieves two basic processing objectives: first, when the slabs come together, the slurry layer deposited on the surfaces of the anode 13 is cut, and secondly, when the plates are in contact as described, a compression effect having a predetermined force and * the idea is to flatten the anode.

After the anode has been pressed, the plates 32 are retracted to the retracted position, the anode is calculated a distance equal to half the distance between the grooves 37 of the plates 35 (Fig. 7), and a second compression cycle as described above is initiated. Finally, the plates 32 are reopened 12 103288 and the anode lowered. Simultaneously, the purification process begins with the nozzle array 36 flushing and, as lowering continues, with pressurized water supplied by the nozzle array 2. The lowering speed can be adjusted to vary the length of time that the pressurized water jets affect the anode. When the lowering is completed, the anode is on top of the carriage 24 (Fig. 2) to allow the process to continue as previously described.

6-8 does not require the high water pressures of the machine shown in Figs. 1-5, and furthermore, the recesses formed on the plate 32 allow the entire deposition layer to be broken even near the anode insulators or any other obstacle protruding from its surface. In addition, the cleaning step is quieter than with rollers.

15 In each of the machine variants described, the components of which they are composed may be arranged in a different order from the one described, and further may even be divided.

20

Claims (14)

A method for cleaning the anodes (13) of electrolytic tanks, in particular for removing impurity deposits which adhere to the surfaces of the anodes 5 (13) in the preparation of non-ferrous metals by the electrolysis method, characterized in that it comprises: infringement; b) removing and separating the broken deposits from the surfaces of the anodes (13); and c) flattening the anode plates (3); wherein the breaking 10 is performed by means of proximal shear lines on the precipitates, and the release and separation step is performed by pressurized water jets on the anode surfaces. Method according to claim 1, characterized in that two groups of cutting lines are cut on the surface of the anode (13) in order to break the precipitates. Method according to Claim 1, characterized in that, before the breaking step, the anodes (13) are subjected to a rinsing operation to remove the acids. Method according to Claim 1 or 2, characterized in that the cutting lines are made in parallel by a pair of rotating rollers (1) having side surfaces provided with screw-like cutting blades, the anodes (13) being fed between the pair of rollers (1) and 1) the difference between the grooves is considered to be approximately equal to the thickness of the anode (13). Method according to Claim 1 or 2, characterized in that the breaking and flattening steps are carried out together by means of two plates (3), one surface of which is provided with fine ribs provided with a free cutting edge, the plates (3) facing each other and they are simultaneously pressed against the surfaces of the anode (13), one on each side, to form shear lines 35 simultaneously and to flatten the anode (13). 14 103288 Machine for cleaning the anodes (13) of the electrolytic tanks, in particular for removing impurity deposits adhering to the surfaces of the anodes (13) used in the electrolysis of non-ferrous metals, characterized in that it comprises at least one pair of horizontally cutting rolls (1) disposed at the same height; two sets of nozzles (2) for supplying pressurized water and positioned above the rollers (1); two plates (3) disposed above the nozzles, each supported by their horizontal horizontal axes (4) and having smooth opposing surfaces; and a device 10 (5) for supporting and lifting the anodes between a pair of rollers (1), nozzle sets (2) and plates (3); the pair of rollers being rotatable and separable from the adjustable; and two sets of nozzles (2) and discs (3) in symmetrical positions with respect to the median vertical plane passing between the pair of rollers (1) with nozzles (2) facing a certain angle 15 and rotating about discs (3) about the support shafts (4) , where they are parallel and located at an adjustable distance approximately equal to the thickness of the anodes (13) and an angular open position (3a). Machine according to Claim 6, characterized in that it comprises two pairs of horizontally cutting rollers (1) located at different heights. Machine according to claims 6 and 7, characterized by: *. 25, that the surfaces of the cutting rollers (1) are provided with standard-height screw-shaped cutting grooves. Machine according to claim 8, characterized in that the side surface of each cutting roll is provided with two screw-like grooves 30, which are provided with a cutting edge and which start transversely. and with opposite threads towards the end portions of the rollers (1). Machine according to claims 8 and 9, characterized in that the grooves of each roll (1) extend with opposing threads I with respect to the grooves of the adjacent rolls (1). 15 103288 Machine according to Claim 6, characterized in that the cutting rollers (1) of each pair of rollers are mounted on supports (8) which can be moved in the same plane perpendicular to the rollers (1), the supports (8) being connected by drive cylinders (12) the movement towards the rollers (1) is limited by the stops (31) according to the thickness of the anode (13) and the surface impurity deposits. Machine according to Claim 6, characterized in that each plate (3) is connected on its outer surface to the drive cylinders (12). 10 Machine according to Claim 6, characterized in that the support and lifting device (5) for the anodes (13) comprises a hoist formed of a flat upright body longer than the end of the anode (14), the body being provided below it, with upright edges with opposing projections for supporting the edges of the anode head (14). 13 103288 Machine according to Claim 12, characterized in that the plates (32) are independent, are supported in the parallel position 20 by the actuating cylinders (35) and are provided on their opposite faces with cutting grooves (33), the plates (32) being displaceable in a position , which is equal to the thickness of the anode (13a) and the resting position, where they are separated by a distance greater than the thickness of the anode head (14). : '25 • «m 16 103288